On Aug 3, 5:53 am, Neil Cerutti <[EMAIL PROTECTED]> wrote: > On 2007-08-03, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > > > > > A naive approach to rank ordering (handling ties as well) of nested > > lists may be accomplished via: > > > def rankLists(nestedList): > > def rankList(singleList): > > sortedList = list(singleList) > > sortedList.sort() > > return map(sortedList.index, singleList) > > return map(rankList, nestedList) > > > >>> unranked = [ [ 1, 2, 3, 4, 5 ], [ 3, 1, 5, 2, 4 ], [ -1.1, 2.2, > > 0, -1.1, 13 ] ] > > >>> print rankLists(unranked) > > > [[0, 1, 2, 3, 4], [2, 0, 4, 1, 3], [0, 3, 2, 0, 4]] > > > This works nicely when the dimensions of the nested list are > > small. It is slow when they are big. Can someone suggest a > > clever way to speed it up? > > Use binary search instead of linear. > > import bisect > import functools > > def rankLists(nestedList): > def rankList(singleList): > sortedList = list(sorted(singleList)) > return map(functools.partial(bisect.bisect_left, sortedList), singleList) > return map(rankList, nestedList) > > -- > Neil Cerutti > Facts are stupid things. --Ronald Reagan
Very clean and precisely what I was looking for. Thanks for expanding my knowledge of the language. -- http://mail.python.org/mailman/listinfo/python-list
